DMD PCB Grounding via Metal Leaf Springs
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Solution Overview
Problem
Conventional image projection apparatuses face challenges in reducing electrical noise, which increases the size of the apparatus when shield structures are added to prevent noise leakage, especially when using digital micro-mirror devices (DMDs) with vertically and horizontally arranged circuit boards.
Innovation Solution
The apparatus employs a metal earth plate with metal leaf-spring members to establish efficient grounding connections between the DMD PCB and the optical illuminating unit, effectively reducing electrical noise by grounding both the front and back sides of the DMD PCB near the connectors, while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield structure is added to prevent electrical noise leakage from the connector, then electrical noise reduction is improved, but the volume size of the image projection apparatus increases
Solution Approach 1:
A metal earth plate is introduced as an intermediary component between the connector and the apparatus chassis. The earth plate provides a dedicated grounding path for electrical noise, acting as a mediator that captures and directs noise away from sensitive components without requiring a bulky shield structure. The metal leaf-spring members serve as flexible connectors between the earth plate and grounding points, further enabling noise dissipation in a compact manner.
Solution Approach 2:
Instead of providing uniform shielding across the entire apparatus, the invention applies grounding specifically at the critical location near the connector where electrical noise is generated. The metal earth plate is positioned adjacent to the connector, and the metal leaf-spring members make contact with the circuit board at the noise-prone area, providing localized noise reduction without increasing overall apparatus volume.
2Volume of stationary object
If the DMD PCB and main circuit board are arranged perpendicular to each other for compact design, then device integration is improved, but electrical noise generation increases due to connector proximity
Solution Approach 1:
The harmful electrical noise is extracted and isolated from the main circuit board by providing a separate grounding path through the metal earth plate. The earth plate is specifically positioned to capture noise from the DMD PCB near the connector area, separating the noise dissipation function from the main signal processing function and preventing noise interference with other components.
Solution Approach 2:
The metal leaf-spring members provide a dynamic, flexible connection between the DMD PCB and the metal earth plate. These spring members can adapt to manufacturing tolerances and thermal expansion, maintaining reliable electrical contact for noise grounding while allowing the perpendicular arrangement of circuit boards to be maintained for compact design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces electrical noise, allowing for a more compact image projection apparatus without increasing its size, thereby enhancing its portability and performance.
Implementation Method 1
metal leaf-spring members that extend along a lengthwise direction of the DMD PCB with both end surfaces of the metal leaf-spring members serving as contact surfaces that come into contact with the front surface and the back surface of the DMD PCB, respectively
Data Source
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AI summary
According to an embodiment of the invention, an image projection apparatus (1) includes: a light source device (20); a first circuit board (42) including an image display device (41) configured to form an image using light, a connector (42a), and an electrically conductive portion (45, 46) near the connector (42a); a retaining member (56) made of metal; an optical illuminating unit (31) held by the retaining member (56) and configured to guide the light to the image display device (41); an optical projecting unit (33) configured to project the image onto a projection surface (2); a second circuit board (80) configured to be electrically connected to the connector (42a); a metal plate (70) fixed and electrically connected to the retaining member; and an elastic metal member (73, 74) arranged on the metal plate (70). The first circuit board (42) is fixed to the retaining member. The elastic metal member (73, 74) is in contact with the electrically conductive portion (45, 46). The second circuit board (80) is fixed and electrically connected to the metal plate (70).